Physical activity has been shown to have beneficial effects on several important health outcomes (coronary heart disease, stroke, hypertension, osteoporosis). However, the physical activity level of the adult population is low. A major public health challenge is to increase the activity level of older people who often have a lifetime history of sedentary behavior, to a level beneficial for health. This proposed demonstration and education project will address this well recognized problem. Specially, we will combine the expertise and experience of The Miriam Hospital Division of Behavioral Medicine, the New England Research Institute, and the Brown University Center for Gerontology and Health Care Research to implement and evaluate the effectiveness of an office- based, physician-delivered intervention to increase the physical activity of sedentary older people. The major aims of this project are: 1. To experimentally evaluate whether the mean activity level of sedentary older patients in physician practices administered a multi- disciplinary stage-matched activity intervention can be increased compared to the mean patient activity level of practices administering usual care; 2. To assess the degree to which changes in physical activity are maintained over a six month follow-up period after withdrawal of the intervention, and; 3. To identify patient, physician and office organizational characteristics that influence the effectiveness of the intervention program. We will conduct a six month physician-delivered intervention within office practices designed specifically to increase physical activity in sedentary older patients. The intervention will be base on the Transtheoretical Model of Behavior Change. The major components of the intervention will be: (1) physician training in office-based counseling; (2) individualized patient counseling; (3) physician support system; and (4) monitoring/follow-up. The major outcome variables will be physical activity level and stage of adoption of physical activity. The maintenance of change in patient physical activity and stage of adoption will be assessed during a six month follow-up period. Patient data relative to the major outcomes will be collected at baseline, 6 weeks, and 6 and 12 months following the baseline visit. Physician and office organization data will be assessed at the time of recruitment and the end of the intervention period. Process data on the quantity and quality of the intervention will also be assessed.